This invention relates to tools for machining materials and to a method of producing such tools.
It is generally known at the present time that hard layers on the basis of carbides, nitrides, carbonitrides, borides, silicides, and oxides of elements of Groups III-VIII of the periodic table have wear-resistant properties. Such layers or cases have very high coefficients of hardness ranging from 1,500 HV to 4,000 HV and more.
One of the most well-known fields of application world-wide is the coating of cutting tools of hard metal, high-speed steel, and tool steel with hard solids, e.g., TiC, TiN, TiNC, etc., whereby substantial improvements in edge life can be achieved. Examples of such cutting tools are reversible carbide tips, milling cutters, reamers, drills, etc. The thickness of these coatings, or combinations thereof, is preferably between 2 and 5 microns. It is limited by the ductility and adhesive strength of the coating on the substrate material. The action of the coating is attributed to the high degree of hardness and wear-resistance in that metal-to-metal contact can be avoided during machining at high pressure and occasionally high temperatures, and hence no local welding together takes place.
It has been shown in practice that in the case of certain alloys and types of steel, tools coated with hard solids do not yield the expected cutting performance. Such alloys to be machined are, for example, aluminum alloys, titanium alloys, and nickel alloys. For this reason, uncoated tools, or tools of hard metal, are frequently utilized at present for machining the aforementioned materials.